1. Field of Invention
This invention relates to ornamental wheel covers and in particular, wheel covers that employ a plastic insert for lightweight reinforcement and decorative ornamentation of the wheel cover.
2. Description of the Prior Art
Use of ornamental wheel covers is widely known in the art. To effectuate cost savings and weight reduction in the wheel cover ornamentation, lightweight plastic inserts can be used in the wheel cover assembly. In one type of wheel cover, the insert is fitted between a decorative, outer sheet metal member and a sheet metal retaining ring. The insert provides lightweight reinforcement of the wheel cover and in some cases, decorative outer ornamentation. The retaining ring includes a plurality of deflectable retaining fingers that rigidly engage the inner surface of the wheel rim upon installation of the wheel cover.
An attractive arrangement in assembling this type of wheel ornamentation is shown in U.S. Pat. Nos. 4,220,373 and 4,295,685. The outer edge of the outer metal ornamental member is generally folded around the outer edge of the insert and the inboard surface of the retaining ring flange to hold the assembly together. There is a limitation as to how much pressure can be applied to the outer edges of the wheel cover assembly. If too much pressure is applied, the outer perimeter of the plastic insert could be crushed and damaged. Thus, tolerances during assembly become critical. In these two patents, the retainer flange that is captured by the outer flange of the outer ornamental member is flat and directly abuts the outer peripheral flange of the insert. Thus, the movement of the forming dies and the amount of pressure applied to fold the outer flange around the insert and the retainer must be critically monitored. Too much pressure may cause the outer edge of the insert to be crushed while too little pressure, which could result from wear in the forming dies or tolerance variations, will not effectively prevent relative rotation of the elements as is essential for proper assembly. Even though it has been found that the metal on metal contact at the outer edges of the wheel cover between the outer ornamental member and the retaining ring tends to prevent their relative rotation, it is not uncommon for the forces in the wheel cover, due to acceleration and deceleration of the wheel, to cause relative slipping of the plastic insert. Several methods have been developed to prevent this.
In U.S. Pat. No. 4,220,373, an axially extending stop portion is integrally formed on the plastic insert to be received in a single notch that is formed on the retaining ring. Thus, not only is there additional fabrication steps required for both the plastic insert and the retaining ring, the insert and the retaining ring must be accurately aligned during assembly to effectuate the interference connection between the stop and the notch.
In U.S. Pat. No. 4,295,685 the plastic insert is preferably coupled to the outer ornamental member, rather than the retaining ring, by a set of screws that pass through the plastic insert and are threadably engaged in an outer hub cap, thus directly fastening the outer member to the plastic insert. Again, this requires additional fabrication of the plastic insert and additional alignment considerations during the wheel cover assembly. It should be noted that in one embodiment, the retaining ring is held in position by bending a flange on the outer member around the retaining ring. As mentioned, such a configuration would require critical monitoring during assembly and most likely some axially extending portions on the outer surface of the plastic insert that match the inside surface of the metal ornamental cover to prevent relative rotation of the elements.
Although the above patents illustrate the generally preferred methods of assembly, other patents disclose methods of directly connecting the plastic insert to the retaining means.
U.S. Pat. Nos. 3,252,738 and 4,007,967 use integral locking pins in the plastic insert fitted through holes in the retaining ring. The pins are fitted or riveted to prevent relative separation movement.
In U.S. Pat. Nos. 3,416,840, 3,601,449, 3,876,257 and 4,328,997, the retaining means has gripping fingers that engage an axially inwardly extending annular flange at the outer perimeter of the plastic insert to prevent rotation of the retaining means relative to the plastic insert.
As can be seen, all the cited wheel covers require specially formed and complicated inserts or retaining rings or both. In addition, the fabrication tolerances are critical. In arrangements that require the retaining ring to be inserted into or over a flange on the insert or require the retaining ring to be mated with integral plastic pins or stops, variation in component diameters or stop locations due to low tolerances, wear in the forming dies, or expansion and contraction of the work pieces, can result in an inability to assemble the wheel cover. Also, additional steps in the fabrication and assembly of the wheel cover may be required. For example, the fabrication of a retaining ring will require an extra operation if holes must cut in the retaining ring for the integral plastic pins of the plastic insert to fit therethrough.